vmscan: only defer compaction for failed order and higher
Currently a failed order-9 (transparent hugepage) compaction can lead to memory compaction being temporarily disabled for a memory zone. Even if we only need compaction for an order 2 allocation, eg. for jumbo frames networking. The fix is relatively straightforward: keep track of the highest order at which compaction is succeeding, and only defer compaction for orders at which compaction is failing. Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Hillf Danton <dhillf@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -34,20 +34,26 @@ extern unsigned long compaction_suitable(struct zone *zone, int order);
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* allocation success. 1 << compact_defer_limit compactions are skipped up
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* to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
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*/
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static inline void defer_compaction(struct zone *zone)
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static inline void defer_compaction(struct zone *zone, int order)
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{
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zone->compact_considered = 0;
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zone->compact_defer_shift++;
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if (order < zone->compact_order_failed)
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zone->compact_order_failed = order;
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if (zone->compact_defer_shift > COMPACT_MAX_DEFER_SHIFT)
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zone->compact_defer_shift = COMPACT_MAX_DEFER_SHIFT;
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}
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/* Returns true if compaction should be skipped this time */
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static inline bool compaction_deferred(struct zone *zone)
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static inline bool compaction_deferred(struct zone *zone, int order)
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{
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unsigned long defer_limit = 1UL << zone->compact_defer_shift;
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if (order < zone->compact_order_failed)
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return false;
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/* Avoid possible overflow */
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if (++zone->compact_considered > defer_limit)
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zone->compact_considered = defer_limit;
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@ -73,11 +79,11 @@ static inline unsigned long compaction_suitable(struct zone *zone, int order)
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return COMPACT_SKIPPED;
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}
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static inline void defer_compaction(struct zone *zone)
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static inline void defer_compaction(struct zone *zone, int order)
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{
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}
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static inline bool compaction_deferred(struct zone *zone)
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static inline bool compaction_deferred(struct zone *zone, int order)
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{
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return 1;
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}
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@ -365,6 +365,7 @@ struct zone {
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*/
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unsigned int compact_considered;
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unsigned int compact_defer_shift;
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int compact_order_failed;
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#endif
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ZONE_PADDING(_pad1_)
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@ -695,9 +695,19 @@ static int __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
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INIT_LIST_HEAD(&cc->freepages);
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INIT_LIST_HEAD(&cc->migratepages);
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if (cc->order < 0 || !compaction_deferred(zone))
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if (cc->order < 0 || !compaction_deferred(zone, cc->order))
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compact_zone(zone, cc);
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if (cc->order > 0) {
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int ok = zone_watermark_ok(zone, cc->order,
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low_wmark_pages(zone), 0, 0);
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if (ok && cc->order > zone->compact_order_failed)
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zone->compact_order_failed = cc->order + 1;
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/* Currently async compaction is never deferred. */
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else if (!ok && cc->sync)
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defer_compaction(zone, cc->order);
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}
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VM_BUG_ON(!list_empty(&cc->freepages));
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VM_BUG_ON(!list_empty(&cc->migratepages));
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}
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@ -1990,7 +1990,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
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if (!order)
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return NULL;
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if (compaction_deferred(preferred_zone)) {
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if (compaction_deferred(preferred_zone, order)) {
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*deferred_compaction = true;
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return NULL;
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}
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@ -2012,6 +2012,8 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
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if (page) {
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preferred_zone->compact_considered = 0;
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preferred_zone->compact_defer_shift = 0;
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if (order >= preferred_zone->compact_order_failed)
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preferred_zone->compact_order_failed = order + 1;
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count_vm_event(COMPACTSUCCESS);
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return page;
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}
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@ -2028,7 +2030,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
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* defer if the failure was a sync compaction failure.
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*/
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if (sync_migration)
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defer_compaction(preferred_zone);
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defer_compaction(preferred_zone, order);
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cond_resched();
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}
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@ -2198,7 +2198,7 @@ static inline bool compaction_ready(struct zone *zone, struct scan_control *sc)
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* If compaction is deferred, reclaim up to a point where
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* compaction will have a chance of success when re-enabled
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*/
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if (compaction_deferred(zone))
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if (compaction_deferred(zone, sc->order))
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return watermark_ok;
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/* If compaction is not ready to start, keep reclaiming */
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